Several medical diagnostic instruments are commonly used by physicians, clinicians, and other caregivers for conducting various facets of a patient examination; for example, a typical wellness visit. These diagnostic instruments are typically directed to specific medical targets; for example, otoscopes are used for examining the ear, ophthalmoscopes are used for examining the eye, rhinoscopes are used for examining the nose, and larygnoscopes are used for examining the throat, among others. Typical versions of these instruments, such as those manufactured and sold by Welch Allyn, Inc. of Skaneateles Falls, N.Y., are designed to be held within a single hand of a caregiver. More specifically, each instrument typically is defined by a compact housing that retains an illumination system configured for adequately visualizing the intended target, either using the eye of the caregiver or electronically in which an image of the target is focused by a contained optical assembly onto an imager.
Early versions of the above-noted instruments, such as described in U.S. Pat. Nos. 3,728,998 and 4,006,738, employ incandescent or halogen bulbs as light sources. While providing adequate illumination of the intended medical target for viewing purposes, light bulbs generate high amounts of heat and power consumption and also have a relatively short working life.
In order to tend to these issues alternative illumination sources have been introduced, such as light emitting diodes (LEDs), for use in medical diagnostic instruments. LEDs generate considerably less heat, require less power, and also have increased working life as compared to halogen and incandescent bulb counterparts. Conversely, LEDs generate less light, which can create issues given the nature of some medical targets (e.g., the ear) and also have spectral issues in terms of their color temperature, the latter being a specific concern for various medical applications in which emission of white light is preferred. In some instances, instruments have been equipped with multiple LEDs disposed in a ring or other similar configuration in order to provide sufficient amounts of illumination to a medical target. In these latter instances, however, the light beam that is produced fails to produce a coherent and uniform spot.